Latching mechanism



Feb. 29, 1944. H. L. PEEK LATCHING MECHANISM Filed May 15. 1942 A I l i I WITNESSES:

:NVENT R Henry L. /%el ATTORNE Patented Feb. 29, 1944 LATCHING MECHANISD I Henry L. Peek, Edgewood, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application May 15, 1942, Serial No. 443,041

10 Claims.

The invention relates to circuit breakers and more particularly to latch mechanism for circuit breakers.

One object of the invention is the provision of an improved latching mechanism for a circuit breaker in which means is provided for utilizing the kinetic energy of the main operating lever or breaker to efiect high speed relatching of the operating mechanism.

Another object of the invention is the provision of an improved latching mechanism for a circuit breaker wherein a rebound preventing means is operated by the main operating lever to insure latching of said lever in closed position.

Another object of the invention is the provision of an improved latching mechanism for a circuit breaker wherein a pivoted mass is operated by the main operating lever as said lever approaches latching position to prevent rebound of the main latch from latching position.

Another object of the invention is the provision of an improved latching mechanism for a circuit breaker that is simple, reliable in operation and inexpensive to manufacture.

The novel features that are considered characteristic of the invention are set forth in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof will be best understood from the following detailed description thereof when read in connection with the accompanying drawing, which comprises an elevational view partly in section of a circuit breaker operating mechanism embodying the principles of the invention.

The circuit breaker, not shown, may be of any conventional construction either of the oil break, air break or gas blast type, and is adapted to be operated to the closed position by means of the operating mechanism illustrated in the drawing.

Referring to the drawing, the operating mechanism includes a main casting l l which is formed to provide a cylinder l3 closed at the upper end by an integral part of the casting. The lower end of the cylinder 13 is closed by means of a member [5 secured thereto and having a relatively large port ll therein which is open to the atmosphere. An operating lever I9 is pivotally mounted at one end on the casting l l and consists of a pair of spaced parallel levers pivotally connected at one end by means of a pivot pin 2| to the upper ends of a pair of parallel links 23 (only one being shown). The lower ends of the links 23 are pivoted by means of a pivot pin 25 on ears 2'! (only one being shown) projecting from the main casting H. The free ends of the operating levers l9 are rigidly connected by means of a cross member 29 and carry a short shaft 3| therebetween, on which is mounted a roller 33 disposed between the levers IS".

The circuit breaker (not shown) is biased to open circuit position b means of an accelerating spring (also not shown) and is connected to the operating mechanism by means of an operating rod 35. The breaker operating rod 35 is pivotally connected by a pivot pin 31 to the operating lever It.

In order to hold the breaker closed, the operat ing lever I9 is held in the closed position by means of a high speed latching mechanism including a main latch pivotally supported on the main casting ll by means or a pivot pin M. The latch 39 is disposed between the levers I9 and is adapted to engage the roller carried by the free ends of the breaker operating levers It to restrain the operating mechanism and the breaker in closed circuit position. The latch 39 is biased to latching position against a stop 13 by means of a spring pressed plunger which engages a projection 41 of the latch. The plunger 45 is slidably mounted in an opening in a portion of the main casting II and is biased inwardly against the projection 41 of the latch 39 by means or a compression spring 39 surrounding th plunger 45 and disposed between a sleeve iii threaded into the casting II, and the head 01 the plunger. An adjustable nut :33 is provided on the outer end of the plunger 45 to limit the inward movement of the plunger.

The construction oi the latch face of the main latch 39 is such that this latch, by itself, will not serve to hold the breaker operating lever E9 in latching position. An auxiliary latch 55 is provided for engagin and holding the main latch 39 in latching position. The auxiliary latch 55 is pivotally mounted on the casting H by means of a pivot pin '51 and has a latch projection 59 which engages under a tail portion iii of the main latch 39 in the latching position of the latching mechanism. The auxiliary latch 55 is biased to latching position by means of a compression spring 63 seated in a recess in the casting and engaging a projection of the latch 55. The auxiliary latch 55 is also provided with a projection which extends directly over the upper end of a trip plunger 51 of an electromagnetic trip device 69. In addition to the trip plunger til, the trip device comprises an E-shaped core ll of magnetic material, an energizing coil 13 mounted on the center leg of the core 1 l, and a movable armature 15. The trip plunger 6! is secured to the center portion of the armature l5 and extends upwardly through a guide opening in the center portion of the core II and through an opening in the horizontal portion of the main casting I I. The armature I5 is biased downwardly to unattracted position by means of a compression spring I! surrounding the upper portion of the plunger 61 and is disposed between a collar I9 fast on the plunger and a bushing BI which is threaded in the opening of the casting through which the plunger extends.

When the trip device 69 is energized, the armature E5 is moved upwardly against the cor II causing upward movement of the trip plunger 51. The upward movement of the trip plunger rotates the auxiliary latch 55 counterclockwise and disengages the projection 6I of the main 7 latch 39, whereupon the accelerating spring (not shown) of the circuit breaker moves the breaker to the open circuit position, the operating lever I9 being rotated counterclockwise about its pivot 25 by the opening movement of the breaker. During the early part of the opening movement of the operating lever I9, the roller 33 forces the main latch 39 in a counterclockwise direction as it clears the latch. As soon as the roller 33 clears the main latch is, the spring 29 acts to return the latch 35) to latching position.

Means is provided to prevent the restoration of the auxiliary latch 55 to its latching position until the operating lever IQ is returned to closed position. This means comprises a U-shaped holding lever 83, the legs of which are pivotally mounted on the pivot pin 51' on opposite sides of the auxiliary latch 55. The holding lever 83 is biased in a counterclockwise direction by a spring 85 compressed between a spring seat in the casting II and a projection ill of the holding lever. The cross member 89 of the holding lever 83 is disposed directly beneath the free end of the operating lever i9 and thus is heldin inoperative position when the operating lever is in closed position. When the operating lever is released and moves toward open position, the holding lever 83 is rotated counterclockwise at which time a lateral extension 9! of the holding lever 83 engages and holds the auxiliary latch 55 in unlatched position until the breaker operating arm I9 is returned to closed position and the roller '33 is reengaged by the latch face of the main latch 3%. For this purpose, the biasing spring 85 of the holding lever 83 of greater strength than the auxiliary latch biasing spring E3.

The breaker-is adapted to be closed by compressed gas admitted to the cylinder I3 above an operating piston 93. The piston 93 is secured to a piston rod 95 sliclable through an air-tight opening in the top wall of the cylinder II. A connector 9? is threadedly connected to the piston rod 5 and pivotally connected to the pivot pin 37 carried by the operating lever I9, thus directly connecting the piston 93 to the breaker operating rod 35.

Compressed air is admitted from an auxiliary air reservoir or tank 99 to the upper end of the cylinder I3 through an inlet passage Iill controlled by a main inlet valve indicated generally at I03 secured to the side of the casting I I. The opening operation of the main inlet valve IE3 is, in turn, controlled by an electromagnetically operated pilot valve I85. The main inlet valve I533 and the pilot valve I55 are fully disclosed in copending application Serial No. 410,686, filed September 13, 1941, of J. M. Cumming and R. C. Cunningham and assigned to the assignee of the resent invention. For this reason, a detailed latched closed.

disclosure of these elements is not included here in since, for a complete understanding thereof, reference may be had to the above noted application,

he pilot valve 565 is operated by an electromagnet It! which, when energized, causes opening of the pilot valve M5 to admit compressed air from the tank 99 to operate the main inlet valve Hi3. Actuation of the inlet valve admits compressed air to the upper end of the operating cylinder I3 which drives the piston quickly downwardly to close the breaker.

When the mechanism is operated to closed position, the operating lever I9 rotates in a clockwise direction, and near the end of this clockwise travel, the roller 33 engages the inclined surface of the main latch as. As the roller passes along this inclined surface, the latch 39 is rotated counterclockwise until the roller passes the nose of the latch whereupon the retrieving spring 39 restores the main latch 33 to latching position. As the roller 33 passes the nose of the main latch 39, the cross member 29 on the free end of the operating lever Iii engages the free end of the holding lever 83 and rotates the holding lever clockwise to its normal position permitting the spring 53 to restore the auxiliary latch 55 clockwise to latching position.

The main latch 39 has an appreciable mass and, therefore, an appreciable moment of inertia, and a certain length of time elapses before the spring 49 will move the main latch into latching engagement with the roller 33. During the closing operation of the circuit breaker most compressed air operated mechanisms have the compressed air shut oil near the end of the closing stroke and depend upon the kinetic energy of the moving parts to carry the breaker to the fully closed position. Also, since the air pressure in the operating cylinder is reduced by expansion during the closing stroke, there remains less closing pressure near the end of the closing stroke than at the beginning. Ehere exists also the tendency of the moving parts to rebound from the fixed stops as the breaker reaches closed position, and the tension of the breaker accelerating spring to movethe breaker to open position. The additive .eifect of the factors set forth is to reverse the movement of the breaker, after it reaches closed position, so quickly as to, at times, cause failure of the main latch 39 to move into latching engagement with the roller.

One of the principal features of the invention is to provide means for insuring latching engagement of the main latch 39-with the roller 33 at the completion of each full closing stroke of the mechanism to insure thatthe breaker will be This means comprises a U- shaped lever I09, the legs of which are pivotally mounted on the ends ofthe pivot pin 5'! outside the legs of the holding lever 83. The connecting portion I I I of the lever I99 has considerable mass and utilizesthe kinetic energy of the moving operating lever I9 to;deliver a hammer-like blow to the main latch 39' ina directionto cause engagement of the latch with the roller 33 in timed relation when the operating lever It reaches fully closed position.

. The lever IE9 is biased in a counterclockwise directicn to an inoperative position by means of a compression spring H3 having one end disposed in a spring seatin the casting IIand the other end bearing against the lever IP39. The spring. I I 3 normally biasesa projection M5 on the lever I89 into engagement with a stud I projecting laterally from the holding lever 53, thus positioning the free end of the lever we to the left of the main latch 39 a distance sufiicient to permit free unlatching movement thereof when the breaker is tripped in the manner previously described.

Assuming that the circuit breaker is standing open the action of the latch mechanism upon closing the breaker is described as follows: When the roller 33 cleared the nose of the main latch 39 during the opening movement of the breaker, the spring 49 restored the latch to the position in which it appears in the drawing. The holding lever 83 has been rotated counterclockwise by the spring 85 to hold the auxiliary latch 55 in unlatched position. The stud Ill has permitted movement of the lever H19 in a counterclockwise direction. With the parts in the positions described, the inlet valve I83 is operated to open position by admission of compressed air thereto under the control or" the pilot valve 35. Upon opening or the inlet valve compressed air is admitted to the upper end of the cylinder H. The compressed air drives the piston downwardly at high speed to effect closing of the breaker, causing clockwise rotation of the operating lever I9 to closed position. Near the end of the closing movement of the operating lever the roller 33 strikes the inclined surface of the main latch 39 rocking the latch counterclockwise. At approximately the same instant, the cross member 29 on the operating lever I9 strikes the free end of the holding lever 83 and rocks this lever sharply clockwise to free the auxiliary latch 55. This rapid movement of the holding lever 83 is transmitted by means of the stud ill to the lever Hi9 driving this member sharply clockwise so that the heavy cross member HI strikes the latch 39 a sharp blow impelling it to latching position. The auxiliary latch 55, freed when the operating lever is struck the holding lever 83, is moved by its spring as into latching engagement with the latching projection SI of the main latch. Positive and complete latching of the breaker is thus effected to prevent breaker rebound. The spring H3 later restores the lever I639 to the position shown in the drawing so that the breaker is free to trip in response to a tripping impulse.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made in the structural details thereof without departing from some or the essential features of the invention. It is, therefore, desired that the language of the appended claims be interpreted as broadly as the prior art permits.

I claim as my invention:

1. In a latching mechanism for a circuit breaker provided with a biased member operatively connected to the breaker and releasable to effect opening of the circuit, in combination, a main latch biased to latching position for engaging and restraining said member in closed position, an auxiliary latch for holding said main latch in latching position, said auxiliary latch being biased to latching position, and means separate from said latches and operable by said biased member when said member moves to closed position to actuate the main latch to latching position.

2. In a latching mechanism for a circuit breaker provided with a biased member operatively connected to the breaker and releasable to effect opening of the circuit, in combination, a main latch biased to latching position for engaging and restraining said member in a predetermined position, an auxiliary latch biased to a latching position for holding'said main latch in latching po-' sition, a holding member controlled by said biased member for holding said auxiliary latch in released position until said biased member is returned to said predetermined position i'ollowing each release thereof, and a member operable by said holding member upon return of said biased member to the predetermined position to positively actuate the main latch to latching position. I

3. In a latching mechanism for a circuit breaker provided with a biased member releasable to permit opening of the circuit, in combination, a main latch biased to a latching position for engaging and restraining said actuating member in a predetermined position, a pivotally mounted auxiliary latch biased to a latching position for engaging and holding said main latch in latching position, tripping means operable to move said auxiliary latch to released position to eil'ect release or the main latch and the biased member, a lever controlled by the biased member for holding the auxiliary latch in released position until the biased member 15 returned to its predetermined position, upon closing of the breaker, and means pivoted coaxially with the auxiliary latch and operable by said lever when the biased member is returned to its predetermined position ior actuating the main latch to latching position.

4. In a latching mechanism for a circuit breaker provided with a member releasable to effect opening of the circuit, in combination. a main latch biased to latching position for engaging and restraining said member in a predetermined position, a pivotally mounted auxiliary latch biased to latching position for engaging and restraining the main latch in latching position, a holding member pivoted coaxially with the auxiliary latch and controlled by said breaker member for holding the auxiliary latch in released position until the breaker member is returned to the predetermined position, and a lever pivoted coaxially with said auxiliary latch and operable by the breaker member when said member returns to the predetermined position to engage and move the main latch to latching position.

5. In a latching mechanism for a circuit breaker provided with a member releasable to ellect opening of the breaker, in combination, a main latch biased to latching position for engaging and restraining the breaker member in a predetermined position, an auxiliary latch biased to latching position for engaging and holding the main latch in latching position, a pivoted mass separate from said latches extending across the path of movement of the main latch and operable upon return of the breaker member to said predetermined position to engage and move the main latch to latching position.

6. In a latching mechanism for a circuit breaker provided with a member releasable to efiect opening of the breaker, in combination, a main latch for engaging and holding the breaker member in a predetermined position, a pivoted auxiliary latch biased to a latching position for engaging and holding the main latch in latching position, a holding member biased to hold the auxiliary latch in released position and operable by the breaker member upon return of said member to the predetermined position to release said auxiliary latch, and a pivoted member biased to permit movement of the main latch to unlatch the actuating member, said pivoted member being operable by the holding member when said holding member is operated to release the auxiliary latch to engage and positively actuate the main latch to latching position.

7. In a latching mechanism tor a circuit breaker provided With a member connected to said breaker and releasable to effect opening of the circuit, in combination, latch means biased to latching position for engaging and holding said member in closedposition, and means normally disengaged from said latch means and operable by said member When said member moves to closed position to engage and actuate the latch means to latching position.

8. A circuit breaker latching mechanism comprising an operating member connected to the circuit breaker and releasable to efiectopening of the breaker, a latch for engaging and holding said operating member in closed position, said latch being operablev to release the operating member, and a movable mass disposed to permit free movement of said latch to unlatching position, said mass being operable by said operating member upon movement of said member to closed position to apply a force to said latch in a direction to accelerate movement of said latch to latching position.

9. In a circuit breaker provided with an operating member releasable to efiect opening of the breaker, a latching mechanism comprising a latch for engaging and holding said operating member in closed position, biasing means for moving said latch to latching position, and a movable mass normally disposed in a position to permit movement of said latch to unlatching position, said mass being operable upon movement of the operating member to closed position to impinge a blow on the latch in a direction to move the latch to latching position at a greater rate of speed than the biasing means.

10. In a circuit breaker provided with an operating member releasable to effect opening of said breaker and movable to a closed position to close said breaker, a latch for engaging and holding said operating member in closed position, biasing means for moving said latch to latching position and a movable mass operable by said operating member when said member is moved to closed position to accelerate movement of said latch to latching position.

HENRY L. PEEK. 

